William Francis Hagerty IV ( HAG-ər-tee; born August 14, 1959) is an American politician, businessman, and diplomat serving as the junior United States senator from Tennessee since 2021. A member of the Republican Party, he served as the 30th United States ambassador to Japan from 2017 to 2019 under President Donald Trump. Hagerty worked as an economic advisor and White House fellow under President George H. W. Bush. He then began a career in private equity. Hagerty is the co-founder of Hagerty Peterson & Company, a private equity investment firm; he is a former managing director of the firm. From 2011 to 2014, Hagerty served as commissioner of the Tennessee Department of Economic and Community Development. He led a successful effort to bring a Major League Soccer franchise to Nashville. President Donald Trump nominated Hagerty to serve as U.S. ambassador to Japan on March 27, 2017; he was confirmed by the U.S. Senate on July 13, 2017, in an 86–12 vote. Hagerty was sworn in as the 30th United States ambassador to Japan on July 27, 2017; he resigned in July 2019 to run for the U.S. Senate. Hagerty ran in the 2020 election for the U.S. Senate seat being vacated by Lamar Alexander. He won the Republican primary and defeated Democratic nominee Marquita Bradshaw in the general election.